PP period.

Not quite 3 months yet, but my child breastfed for a month, then due to medical problems we switched to formula. (reason why I put that in is because I heard breastfeeding can make it take longer?) I haven't had my postpartum period yet. And even though we have used protection I'm still terrified of being pregnant again.
Is it normal to go this long without one? I mean I used to be very irregular, so I'm not sure if that's changed or not..
This probably sounds stupid, hopefully someone understands what I'm saying.  

yeah, sometimes it can take a few months for it to come back, even if you aren't BFing. I think I heard something like 6-24 weeks.